BASIDIOLICHENES (Hymenolichenes)
Cora, Dictyonema (incl. Laudatea), Corell¢ (doubtfully placed here as the hymenium is unknown).
Habitats and Distribution of Lichens.
1. Habitats.—These are extremely varied, and comprise a great number of very different substrata. Chiefly, however, they are the bark of trees, rocks, the ground, mosses and, rarely, perennial leaves. (a) With respect to corticolous lichens, some prefer the rugged bark of old trees (e.g. Ramalina, Parmelia, Stictei) and others the smooth bark of young trees and shrubs (e.g. Graphidei and some Lecideae). Many are found principally in large forests (e.g. Usnea, Alectoria jubata); while a few occur more especially on trees by roadsides (e.g. Physcia parietina and Ph. pulverulenta). In connexion with corticolous lichens may be mentioned those lignicole species which grow on decayed, or decaying wood of trees and on old pales (e.g. Caliciei, various Lecideae, hylographa), (b) As to saxicolous lichens, which occur on rocks and stones, they may be divided into two sections, viz. calcicolous and calcifugous. To the former belong such as are found on calcareous and cretaceous rocks, and the mortar of walls (e.g. Lecanora calcarea, Lecidea calcivora and several Vcrrucariae), while all other saxicolous lichens may be regarded as belonging to the latter, whatever may be the mineralogical character of the substratum. It is here worthy of notice that the apothecia of several calcicolous lichens (e.g. Lecanora Prevostii, Lecidea calcivora) have the power of forming minute cavities in the rock, in which they are partially buried. (c) With respect to terrestrial species, some prefer peaty soil (e.g. Cladonia, Lecidea decolorans), others calcareous soil (e.g. Lecanora crassa, Lecidea decipiens), others sandy soil or hardened mud (e.g. Collema limosum, Peltidea venosa); while many may be found growing on all kinds of soil, from the sands of the sea-shore to the granitic detritus of lofty mountains, with the exception of course of cultivated ground, there being no agrarian lichens. (d) Muscicolous lichens again are such as are most frequently met with on decayed mosses and Jungermannia, whether on the ground, trees or rocks (e.g. Leptogium muscicola, Gomphillus calicioides). (e) The epiphyllous species are very peculiar as occurring upon perennial leaves of certain trees and shrubs, whose vitality is not at all affected by their presence as it is by that of fungi. In so far, however, as is known, they are very limited in number (e.g. Lecidea, Bouteillei, Strigula).
Sometimes various lichens occur abnormally in such unexpected habitats as dried dung of sheep, bleached bones of reindeer and whales, old leather, iron and glass, in districts where the species are abundant. It is apparent that in many cases lichens are quite indifferent to the substrata on which they occur, whence we infer that the preference of several for certain substrata depends upon the temperature of the locality
BIBLIociAPHV.-General: Engler and Prantl, Die naturlichen Pfl¢nzenf¢milien, Tell 1, Abt. I * where full literature will be found up to 1898. M. Funfstuck, " Der gegenwartige Stand der Flechtenkunde," Refer. Generalvers. d. dent. bot. Ges. (19902). Dual Nature: J. Baranetzky, " Beitrage zur Kenntnis des selbststandigen Lebens der Flechtengonidien," Prings. Jahrb. f. wiss. Bot. vii. (1869); E. Bornet, " Recherches sur les gonidies des lichens,". Anna de sci. nat. bot., 5 ser. n. 17 (1873) ; G. Bonnier, Recherches sur la synthese des lichens," Ann. de sci. nat. bot., 7 ser. n. 9 (1889) ; A. Famintzin and J. Baranetzky, "Zur Entwickelungsgeschichte der Gonidien u. Zoosporenbildung der Lichenen," Bot. Zeit. (1867, p. 189, 1868, p. 169) ; S. Schwendener, Die Algentypen der Flechtengonidien (Basel, 1869) ; A. M611er, Uber die Kultur flechtenbildender Ascomyceten aline Algen. (Munster, 1887). Sexuality: E. Stahl, Beitrage zur,. Entwickelungsgeschichte der Flechten (Leipzig, 1877),; G. Lindau, Uber Anlage and Entwickelung einigerFlechtenapothecien (Flora, 1888) ; E. Baur, " Zur Frage nach der Sexualitat der Collemaceae," Ber. d. dent. bot. Ges. (1898); " Uber Anlage and
Entwickelung einiger Flechtenapothecien " (Flora, Bd. 88, 1901) ; " Untersuchungen fiber die Entwickelungsgeschichte der Flechtenapothecien," Bot. Zeit. (1904) ; 0. V. Darbishire," Uber die Apothecium-entwiekelung der Flechte, Physcia pulverulenta," Nye. Prings. Jahrb. (Bd. 34, 190o). Chemistry.—W. Zopf, " Vergleichende Produkte," Beitr. z. bot. Centralbl. (Bd. 14, 1903) ; Die Flechtenstoffe (Jena, 1907). U. M. C.; V. H. B.)